Technical Info - Crystals
PACKAGE
Physical holder of the crystal unit.
PARABOLIC TEMPERATURE CURVE
BT-cut and Tuning Fork crystal frequencies follow a parabolic curve over temperature. The frequency will decrease as the temperature goes above or below the turnover temperature.
PARALLEL RESONANT. PL
A parallel resonant oscillator circuit uses a crystal unit that is designed to operate with a specified value of load capacitance. This will result in a crystal frequency higher than the series resonant frequency, but lower than the true parallel resonant frequency.
pF
The abbreviation for "picoFarad" used to describe a fractional part 10-12, (one trillionth) of one Farad.
Pico
A prefix used to describe a sub-multiple of a number. One Pico is one-trillionth, 10-12, of a unit.
PLATE
The quartz blank or resonator.
POLISH
A process used in the manufacture of some types of quartz crystals. The polish process results in a very fine surface finish. The word "polish" is also used to define the material used in the polish process, as well as the process itself.
PPM
The abbreviation for "Parts Per Million" a method of calculation used to specify the permissible frequency deviation of a crystal or oscillator. May also be seen as "PPM", both are correct.
PULLABILITY
The change in frequency of a crystal unit, either from the natural resonant frequency, Fr to a load resonant frequency, FL or from one load resonant frequency to another. The frequency can be pulled in a parallel resonant circuit by changing the value of load capacitance. A decrease in load capacitance causes an increase in frequency, and an increase in load capacitance causes a decrease in frequency.
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